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Lifetime Measurements of Neutron-Rich Carbon and Oxygen Isotopes Experiment at GANIL

Explore excited states in C and O isotopes to test three-body forces. Collaboration by IFJ PAN Krakow and Milano, using AGATA and VAMOS technologies for lifetime measurement and analysis. Experimental setup, tracking, Doppler correction, simulations, and results comparison discussed.

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Lifetime Measurements of Neutron-Rich Carbon and Oxygen Isotopes Experiment at GANIL

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  1. Status of the experiment E676@GANIL: Lifetime measurements of excited states in neutron-rich C and O isotopes as a test of the three-body forces M. CiemaŁa, IFJ PAN Krakow Spokespersons: S. Leoni, B. Fornal, M. Ciemala Milano – IFJ PAN Krakow Local Contact: G. DeFrance, M. Ciemala AGATA@GANIL Collaboration, Coordinators: E. Clement, S. Lenzi VAMOS Collaboration, Coordinator: M. Rejmund, GANIL, Caen PARIS Collaboration, CoordinatorA. Maj, IFJ PAN, Krakow NuSpIn 2019 27.06.2019

  2. 82 126 Proton number Z 20O 16C r-processpath 50 18O terra incognita 82 18O 28 50 20 8 28 20 2 Increasedsensitivity of someelectromagneticobservables to the details of n-n force 2 8 Neutron number N

  3. ab initio Many-Body-Pert. Theorycalculations of the 2+2 lifetimes Z 20O 16C NN NNN 0.3 ps 0.08 ps NN NNN 0.32ps 0.20ps 50 18O ab initio No-Core-SHELL Model calculations ≈ 15 ps 11 ps N 16C 20O M. Wiedeking et al., Phys. Rev. Lett. 94, 132501 (2005). M. Petri et al., Phys. Rev. C 86, 044329 (2012).

  4. Experimental setup E676@GANIL 16C + 183-xnRe 18O +181Ta  20O+ 181-xnTa 16C 20O PARIS clusters target VAMOS@45 degree  PARIS clusters Thicktarget + degrader (also plunger) AGATA 31detectors 18O Beam

  5. VAMOS A, Z, selection Z = 8 A gate for Z = 8 Identifiedisotopesfrom B to F: AGATA replay - tunedparameters S. Zilianiand F. Crespi(U. of Milano) N isotopes –S. Zilianitalk latertoday

  6. PARIS timing – correction to velocity We measure V by path in spectrometerand timebetweenRF and Plasticat the end of focalplane. 18O MASS reconstruction with RF Time of experiment But RFsignalisNOTstable in time in respect to beam on target – bestobservableis Mass (calculated from Brho and V) We areusing PARIS (LaBr part) vs. RF timing to correct RF fluctiations (up to 2 ns, epseciallyat the end of exp.)

  7. PARIS timing – correction to velocity We measure V by: measurepath in spectrometerand timebetweenRF and Plasticat the end of focalplane. 18O MASS reconstruction with RF+PARIS !!! Time of experiment Thanks to PARIS timing we recoveredgood Areconstruction/stability (itmeansalsogood V)! We areusing (mean) PARIS vs. RF timing to correct RF fluctiations(up to 2 ns, epseciallyat the end of exp.)

  8. AGATA Spectra–Tracked and Doppler Corrected 16C 19O 16C 19O 20O gated by VAMOS 20O

  9. METHOD: Doppler shift dependence on the point of gamma emission ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ ∿ 20O velocity Distribution Measured in VAMOS 18O (7 MeV/A) + 181Ta target (6 mg/cm2) target  thick target Reconstructed initial 20O velocity distribution Inside thick target Beam Beam 18O 18O

  10. Simulationsareneeded to extractlifetimes from glineshape The beam is passing through the target decreasing its energy. Multi nucleon transfer reactions occur inside the target. An excited level is let to decay with fixed lifetime. Simulation(with GEANT4 package) of AGATA response. 20O gpeak 2+10+ long Lifetime 10.5 ps AGATA simulated data are tracked (similarly to experimental data) and Doppler corrected. Experimental energy resolution of AGATA crystals and differences in counting rates are included in the simulation. 2D chi2mapsareused to determine optimum lifetime.

  11. LONG Lifetime test – 20O 2+10+, 10.5 ps t [ps] 20O 1674 Eg

  12. TEST of KNOWN Lifetimes in the 100s femtoseconds region 92(19) fs 19O 130° 18O (7 MeV/A) + 181Ta target (6 mg/cm2) 19O t 2779 +50 t = 140 fs 150° -40 170° Eg • Veryold • litteraturevalues (1971) • = 70(26) fs • = 117(26) fs

  13. TEST of KNOWN Lifetimes in the 100s femtoseconds region 17O 115(72) fs 130° 18O (7 MeV/A) + 181Ta target (6 mg/cm2) 2184 t 17O 17O +40 t = 159 fs 150° -20 Eg 170° • Veryold • litteraturevalues (1964) • = 120(+80,-60) fs

  14. OUR Case of interest–20O 18O (7 MeV/A) + 181Ta target (6 mg/cm2) 20O 130° 2396 20O 130° t +80 t = 150 fs 150° -30 150° 170° 170° Eg ab initiopredictions 3 body force t = 200 fs 2 body force t = 320 fs

  15. Large improvement with AGATA 20O FULL Tracking 2+2 2+1 (2396 keV) 130° 20O Center Front Segment 150°

  16. OUR Case of interest–16C 18O (7 MeV/A) + 181Ta target (6 mg/cm2) 16C t 16C Eg ab initiopredictions 3 body force t = 80 fs 2 body force t = 340 fs

  17. Summary:Theory vs. exp. resultscomparison For 16C most precisemeasurement givesE = 2217(2) keV, which do not allow to determineexactlifetimevalue(for now). NO sensitivitywould be obtained with conventionalHPGe detectors

  18. Conclusions • Italian-Polish-French collaborationallows to performsuccessfulexperiemntat GANIL with combined AGATA+VAMOS+PARIS setup. • (Re)-measurement of 17O (½- state) and 19O (7/2+state) lifetimes – confirmationthat DSAM method for AGATA and simultionsworkswell. • We measuredlifetime of second 2+ in 20O: 150fs, whichisconsistent with the calculationsincludingthree body interactions. AGATA trackingcrucial for obtainingresults. • Extractedestimates of lifetime in 16C whichdepend on non-shifted gamma-rayenergy. • Draft of publicationsend to co-authors. • N isotopes –S. Ziliani talk today.

  19. Acknowledgements S. Leoni, F. C.L. Crespi, S. Ziliani, G. Benzoni, C. Boiano, S. Bottoni, A. Bracco, S. Brambilla, F. Camera, B. Million, O. Wieland; Univ. and INFN Milano, Italy • B. Fornal, M. C., A. Maj, P. Bednarczyk, N. Cieplicka-Orynczak , J. Grębosz, L. W. Iskra, M. Krzysiek, M. Kmiecik, K. Mazurek, B. Wasilewska; IFJ PAN Krakow, Poland • E. Clement, G. de France, B. Jacquot, Y. Kim, A. Lemasson, H. Li, C. Michelagnoli, M. Rejmund; GANIL Caen, France D. Mengoni, F. Recchia, D. Bazzacco, S. Lenzi, S. Lunardi, J. Valiente-Dobon, DeAngelis, D. Napoli; INFN LNL, INFN Padova, Univ. of Padova • A. Dewald, C. Fransen, C. Müller-Gatermann, M. Bast, M. Beckers, T. Braunroth, A. Goldkuhle; Univ. of Koeln • O. Dorvaux, S. Kihel, C. Schmitt; CNRS/IN2P3, Strasbourg, France • I. Matea, I. Stefan; IPN Orsay, France • P. Napiorkowski, M. Matejska-Minda; HIL UW, Warsaw, Poland • M. Harakeh; KVI Univ. Groningen, Netherlands • V. Nanal et al.; Univ. of Calcata, India • M. Kicińska-Habior; Univ.ofWarsaw, Poland • M. Stanoiu; IFIN-HH, Bucharest, Romania • A. Karpov; JINR, Dubna, Russia

  20. NNDC, t < 26 fs

  21. Comparison with ab initio predictions 20O MANY BODY Pert. THEORY Clear need for Three body term NN NN + NNN In-Medium Similarity Renormalization Group (IMSRG) One of mostadvanced approaches (with meson-exchangecurrents) NO sensitivitywould be obtained with conventionalHPGe detectors

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